This invention relates to the forming of fluid-filled shells by passing fluid through nozzles.
Gas-filled shells can be formed by passing a molton material through an outer nozzle and passing a gas through an inner nozzle concentric with the outer nozzle, so that a gas-filled extrusion is created that breaks up into gas-filled spheres. Where the gas-filled spheres, or shells, are to be of uniform size, the extrusion should be of uniform wall thickness. Prior art systems have constructed the nozzle assembly with the inner nozzle held precisely concentric with outer nozzle, to assure that the extrusion will have uniform wall thickness all around its axis.
When small shells are to be constructed of millimeter or submillimeter size, it becomes difficult to precisely center the inner nozzle within the outer nozzle. The difficulty is compounded where the liquid must be at a high temperature and is highly corrosive, as in the case where liquid metal is pumped through the outer nozzle, since many suitable nozzle materials are difficult to machine. Furthermore, the large temperature rises from room temperature to operation temperature, can cause thermal expansions leading to bending of the parts that results in misalignment of the inner and outer nozzles. A nozzle assembly for use in systems for generating shells of small diameter as in the millimeter and submillimeter range, which could be constructed and maintained at moderate cost, would be of benefit in the construction of such systems.